The invention relates to vehicle seats and particularly to multi-passenger seating units for aircraft which are adapted to be mounted to slotted seat tracks which are permanently affixed in the floor of the aircraft cabin. Generally, a plurality of seats, such as three, for example, are supported on an elongated upper seat frame which may include a pair of elongated fore and aft positioned lateral stretcher tubes. A pair of front and rear legs and an upwardly and rearwardly extending connecting brace member are attached at their upper ends to the stretcher tubes intermediate the ends thereof, and to the seat tracks at their lower ends. The tubes permit the end seats, or portions thereof, to be supported in a cantilever fashion. Unfortunately, because seat track locations are determined in the design stage of an aircraft by different factors such as fuselage strength requirements or an assumed seating configuration, there are a number of models of aircraft now in service where the fixed locations of the seat tracks are not where the aircraft operator would like them to be. For example, some three-person seating units have their two rear legs positioned such that they underlie portions of the aisle and/or window seat, making it impossible to fit a conventional carry-on bag or briefcase under one or two of the seats in the unit while the third seat has excess space. This situation is very irritating to passengers and can delay the departure of an aircraft as the cabin attendants attempt to locate an alternate place to store the luggage.
Obviously, it would be highly desirable to be able to position the rear legs of a seat and their support braces in positions where the luggage and foot space under the seats would be generally equalized for all passengers. Such a concept is disclosed to a small degree in McGregor U.S. Pat. No. 3,603,638 assigned to the same assignee as the present application. However, the disclosed structure relates principally to an energy-absorbing construction and includes a front beam member of substantial height which extends the entire width of the seating unit, fore and aft vertical beams which enclose the luggage space under each seat, and a pair of rear legs for each sitting position. The patented design includes a tubular lateral beam or stretcher member which lies on the floor at the rear of the unit and extends for the entire width of the seating unit. It serves to transfer loads transversely from the rear legs to the floor track. The McGregor construction, with its relative massive beams and its use of six legs to support three seats, would be much heavier than currently produced cantilevered seating units which require only two legs. Its weight, considering the high cost of fuel, would make its use in an aircraft quite undesirable. Furthermore, to the extent more than two legs are used, the width of the underseat storage space is considerably restricted and, in a tourist seat, would be insufficient to accommodate standard sizes of luggage placed flat on the floor. A seat used by British Aerospace on its Model 748 aircraft utilizes a triangular cross-section rear floor stretcher connected at its ends to the floor tracks and to a pair of fore and aft tension members which overlie the floor tracks. The construction is used on a double seat that can be placed interchangeably on either side of the aircraft. A single leg attached to the rear floor stretcher is affixed to an upper front frame member between the two seats and is welded to a second diagonal member which joins the front baggage bar to the upper rear frame.